Over the past century the demand for energy has grown exponentially. With the growing demand for energy, many different energy sources have been explored and developed. One of the primary sources for energy has been and continues to be the combustion of hydrocarbons. However, the combustion of hydrocarbons is usually incomplete combustion and releases non-combustibles that contribute to smog as well as other pollutants in varying amounts.
As a result of the pollutants created by the combustion of hydrocarbons, the desire for cleaner and more efficient energy sources has increased in recent years. With the increased interest in cleaner energy sources, fuel cells have become more popular and more sophisticated. Research and devolvement on fuel cells has continued to the point where many speculate that fuel cells will soon compete with the gas turbine generating large amounts of electricity for cities, the internal combustion engine powering automobiles, and batteries that run a variety of small and large electronics. However, there are many applications with a variety of modulating power needs that cannot be met by current fuel cell technology.
Fuel cells conduct an electrochemical energy conversion of fuel and oxidant into electricity and heat. Fuel cells are similar to batteries, but they can be “recharged” while providing power.
Fuel cells provide a DC (direct current) voltage that may be used to power motors, lights, or any number of electrical appliances. There are several different types of fuel cells, each using a different chemistry. Fuel cells are usually classified by the type of electrolyte used. Fuel cells are generally categorized into one of five groups: proton exchange membrane (PEM) fuel cells, alkaline fuel cells (AFC), phosphoric-acid fuel cells (PAFC), solid oxide fuel cells (SOFC), and molten carbonate fuel cells (MCFC).
In general, a fuel cell includes the following basic elements: an anode, a cathode, an electrolyte, and one or more catalysts arranged at the interfaces between the anode and the electrolyte, and the cathode and the electrolyte. Element composition may vary in each of the above-mentioned varieties of fuel cell.
While the development of fuel cells has been rapid in recent years, there are sill several shortcomings. One of the difficulties with current fuel cells is a lack of versatility. Typical fuel cell arrangements are only able to produce power within relatively narrow parameters and are not capable of significant power modulations. However, may modern electronic devices demand multiple voltages and currents that can vary significantly. Thus, typical fuel cells cannot supply power for many of today's modern electronic devices.